How to Skim Coat a Ceiling

Skim coating is the process of applying drywall mud to a wall or ceiling to smooth its surface. A wall or ceiling can be skim coated to cover cracks, imperfections or a previously-applied texture. The mud is applied in multiple coats and fills in low spots until a flat, smooth surface is achieved. For ceiling applications, the existing texture, usually a popcorn finish, must first be scraped off before a skim coat can be applied.

A skim coated ceiling makes for a clean, smooth look.
  1. Climb the ladder and use the 8-inch drywall knife to scrape off existing texture such as popcorn. Hold the knife at a shallow angle and push the edge away from you to scrape.

  2. Use the 8-inch drywall knife to load some drywall mud into the mud pan. Dip the drywall knife into the pan and scoop some mud onto the knife.

  3. Start at one corner of the ceiling and apply mud to the ceiling with the drywall knife. Apply the mud while holding the mud knife at approximately a 30 degree angle. Apply light pressure to the knife as you move it across the ceiling. Repeat this process until the entire ceiling is coated.

  4. Wait approximately 24 hours to allow the mud to dry. Use the drywall knife to gently scrape off overlap ridges and high spots.

  5. Use the 12-inch drywall knife and apply another coat of drywall mud to the ceiling, continuing to fill in the low spots and cracks. Wait another 24 hours until the second coat dries. Repeat this process until all low spots and cracks are filled.

  6. Wait 24 hours for the final coat to cure, then attach a fine drywall sanding screen to the pad on the drywall sanding pole and sand the ceiling. Use long, even strokes and avoid sanding in one spot for too long. Keep sanding until the surface is smooth with no high spots, low spots, cracks or texture.

About the Author

Emrah Oruc is a general contractor, freelance writer and former race-car mechanic who has written professionally since 2000. He has been published in "The Family Handyman" magazine and has experience as a consultant developing and delivering end-user training. Oruc holds a Bachelor of Arts in political science and a minor in economics from the University of Delaware.